1. Technical Field
The present invention relates generally to circuits for driving columns in a display, and more particularly relates to a system and method for adaptively matching a ramp signal to the load characteristics of problematic pixel values in a video display.
2. Related Art
Video display systems have become commonplace in today's electronics marketplace. Laptops, flat screen monitors, televisions, video cameras, digital cameras, personal digital assistants, cell phones, etc., all typically utilize some form of a video display. As the demand for more and more advanced electronic systems continues to grow, the need to provide improved performance for visual displays remains an ongoing challenge.
A typical visual display, such as a liquid crystal display (LCD), is often configured as an active matrix of pixels arranged in a plurality of columns, e.g., up to 1200 or more. Each column includes a “column driver” that is driven by a common or shared signal created by a column driver circuit. During operation of each column driver, data, representing pixel values (e.g., brightness, etc.), is loaded into registers and converted into analog information via a digital-to-analog converter (DAC), which is then displayed. The column driver circuit provides the necessary voltage signal to “drive” the analog information to be displayed for each pixel in the active matrix. A capacitor associated with each pixel location is utilized to maintain the voltage in the pixel for a finite period of time.
Unfortunately, in some display configurations, the column driver signal is subject to varying loads that can result in a mismatch between the signal generator and the load required by the column drivers. When this occurs, horizontal cross talk may result. Accordingly, there exists a need for a column driver system that can address the changing column load characteristics of a display.